British countryside's Victorian era spring is a danger for birds, experts warn

The British countryside experienced a Victorian era-like spring this year as the season spread across the country at a similar rate to the 19th century, forcing experts to issue warnings about the effect it has had on our birds.

The speed at which key signs of spring, such as swallow sightings, moved up the UK from the south coast slowed to 1.2mph in comparison with 1.9mph last year, research showed. This equated to the season taking four weeks to travel the country, instead of three.

Experts have now warned the slow development may have seriously affected nesting birds, causing some broods to die due to a lack of food.

It's without question that wildlife reacts to the arrival of spring flowers and treesDr Kate Lewthwaite

Dr Kate Lewthwaite, a citizen science manager at the Woodland Trust, said it was “without question” that some species of bird, which rely on leafing as an indicator of when to brood their young to ensure a steady source of food, would have been affected.

“Wildlife reacts to the arrival of spring flowers and trees,” she said. “Whilst the analysis perhaps throws up more questions than it answers, it does highlight the delicate balance success and failure is for a number of species.”

The analysis, which was completed by Professor Tim Sparks of Coventry University, suggested the delayed spring was due to the weather, with the country experiencing a mild December before a cooler start to this year.

Greg Dewhurst, a forecaster at the Met Office, said temperatures were more than 2C above average this winter at 6.7C, before dropping in March to just below the norm.

“On some days in March and April the temperatures were cooler than in November and December,” he said. “In terms of this cooling, I can see how this may have created a delay.”

Ben Andrew, a wildlife advisor at the Royal Society for the Protection of Birds (RSPB), told The Daily Telegraph the charity had received a higher number of calls than normal about birds including blue tits and grey tits suddenly dying in their nest boxes.

“Whole broods have died, sometimes even overnight,” he said. “It is not the case that the parents are abandoning these boxes, they have just timed it slightly wrong.”

Mr Andrew explained that species may have been fooled into preparing their nests too early because of the warmer winter. “They have nested and mated in the slightly warmer period. They were fully committed but when the chicks hatched, the temperatures plummeted and the rain washed crucial food such as caterpillars off leaves and trees.”

It is not the case that the parents are abandoning these boxes, they have just timed it slightly wrongBen Andrew

Rare species, such as turtle doves and nightingales, could be affected in the long term by the delayed spring while migrant birds, including swallows and swifts, are understood not to be breeding at the same rate as before, Mr Andrew added.

The analysis, which was released today, used signs including sightings of frogspawn, orange-tip butterflies and oak leaves to determine the “rate of spring”. It put the arrival of the season this year in line with averages from between 1891 and 1947.

Records from the Woodland Trust’s Nature’s Calendar scheme showed this year’s development was much slower than the 1.8mph seen on average between 1998 and last year.

Experts added that the slower spring could not yet be put down to climate change because further seasons would have to be looked at to determine if there is any trend.